Mapping Mountains – Trimble Surveys – Gwaun Ceste

 

17.07.21  Hergest Ridge (SO 246 557), Hergest Ridge (SO 254 562, previously Trimbled) and Hanter Hill (SO 251 570, not Trimbled) 

The Welsh summit of Hergest Ridge (SO 246 557)

The main purpose of this walk was to visit and survey the Welsh summit of Hergest Ridge, which is now classified as a Pedwar under National Top status.  The concept of National Tops is explained in a separate post and for the lists co-authored with Aled Williams affects two hills, the other is Stonewall Hill (SO 318 696) which we visited and surveyed later in the day. 

This walk would also give opportunity to visit the English summit of Hergest Ridge and extend the walk across this hill’s broad summit ridge, to a point marked with a 417m spot height on contemporary Ordnance Survey maps and then also visit the Pedwar of Hanter Hill, with this and its higher neighbour separated at the connecting bwlch by the national border between Wales and England.  As the forecast gave for extremely warm conditions we needed a relatively early start to gain the majority of height before the heat of the day struck. 

We met in Caersŵs just before 8.00am and were parked and walking by 9.00am.  I had visited these hills once before in April 2015, on that occasion I had visited the higher English summit of Hergest Ridge, and not the Welsh summit, and although taking two data sets from the summit area of Hanter Hill, I failed to survey its actual summit, which we later found to be immersed in a mass of gorse. 

Approaching the hills from the west we followed a public footpath that starts as a track leading to Upper Hanter, which was once a farm.  It was already warm and any shaded area on the track proved a welcome relief from the conditions that would increase in ferocity as the day progressed. 

The public footpath leads past the front door of Upper Hanter before continuing as a green track through a gate and then onward through copious amounts of fern.  As we walked past the house we said our ‘hello’s’ to a woman sitting in shade reading.  We chatted for a few moments before waving our goodbyes and continuing up the hill. 

On the path leading to the bwlch between Hanter Hill and the English summit of Hergest Ridge

The greened path crept up hill giving good views of our first objective; the Welsh summit of Hergest Ridge, which from this viewpoint at this time of year shone green with upper slopes of fern, middle slopes consisting of grazing fields and mature trees as foreground, it looked a good hill and one which I had bi-passed when making an ascent from the south-west during my only other visit to the English summit of Hergest Ridge. 

The Welsh summit of Hergest Ridge

The green track eventually led to the connecting bwlch between Hanter Hill and Hergest Ridge; on one side of this bwlch is Wales and on the other, England.  On my previous visit a small conifer plantation was positioned just below the bwlch, this has now gone with the trees cut down. 

Hanter Hill from its connecting bwlch

The bwlch is also the meeting point of a number of tracks; we opted for the track leading to the English summit of Hergest Ridge, leaving Hanter Hill for later.  This ascent proved warm, with the left hand side of the track giving a semblance of shade.  Reaching a T-junction of tracks we then headed south-west loosing height as we did so, aiming for the Welsh summit and leaving the higher English summit until after. 

The new Pedwar is covered by LIDAR, which Aled and I had analysed.  The summit is close to a pool, which today was almost dry with just the last remaining vestiges of water giving some respite to the sheep who visited. 

LIDAR image of the Welsh summit of Hergest Ridge (SO 246 557)

The green track leads to within a few metres of this hill’s high point which consists of a small patch of gorse and fern.  The concept of National Tops was raised a few months ago and we had debated its merits and details on a number of occasions, having done so it was good to now be here standing on the Welsh summit of Hergest Ridge. 

Aled heading toward the Welsh summit of Hergest Ridge

We quickly assessed the lay of land and having decided its high point the Trimble was soon set-up gathering data.  During data collection Aled sat on the green track whilst I stood 50 or so metres away submerged in bracken.  Once allotted data were gathered and stored the equipment was closed down, packed away and I re-joined Aled on the green track and followed him back toward the higher English summit of Hergest Ridge. 

Gathering data at the Welsh summit of Hergest Ridge

The upper part of Hergest Ridge is open and any fences that exist are few and far between.  On a clear day the hill gives excellent walking on greened tracks with extensive views south to the distinctive profile of the Bannau Brycheiniog, east to the Clee Hills and Malvern Hills, and the higher Radnorshire hills to the west and north. 

It was a joy to be back on this hill; however conditions were decidedly warm and only on occasion did a welcome cooling breeze drift across its upper slopes.  We were soon on the higher summit which today had a number of horses beside it.  These slowly moved away as we made our way to the highest rock that constitutes the summit.  It was time for a rest and a bite to eat and the rocks proved an ideal place to sit and recuperate. 

The English summit of Hergest Ridge

We had no firm plan to visit the 417m map heighted top to the north-east, but as another track headed from close to its high point down to the connecting bwlch with Hanter Hill we decided to continue on the main ridge toward it. 

This top is crowned by nine monkey puzzle trees which are an unusual adornment for any summit at this altitude in this country.  Two benches are placed on their periphery and the larger gave another opportunity to sit and rest.  Just below the summit is the Whet Stone, which is marked on the map.  The stone is large, but is not Neolithic and in all likelihood found its way to its present position naturally. 

Monkey Puzzle trees at over 400m

From here it was only a short distance down the track to the bwlch between Hanter Hill and Hergest Ridge.  This bwlch has been Trimbled and LIDARed, therefore a second data set was unnecessary, however I hoped to take a data set from the true summit of Hanter Hill; something I failed to do on my previous visit. 

Hanter Hill from near the Whet Stone

The path leading up Hanter Hill proved a hot plod.  I watched as Aled quickly pulled ahead.  I paced myself going up, stopping once to take on water, look at the expanding view and to take a few photographs.  Soon I reached the hill’s summit area. 

On my previous visit I had taken two data sets from the summit area of Hanter Hill, neither of which matches the position of the summit produced by LIDAR.  This position is submerged in gorse.  As I recovered a modicum of breath I watched as Aled approached the gorse and headed in to it.  I soon followed but wearing shorts later emerged scratched and bloodied, with thorns still sticking in my legs. 

LIDAR image of Hanter Hill (SO 251 570)

When at the high point the gorse proved so dense that when I placed the Trimble on top of it, it remained in place.  Because of this I wondered about gathering data, but the thought of kneeling to take a measurement offset, coupled with four journeys in and out of the gorse waiting for the Trimble to achieve its 0.1m accuracy level before data should be locked and then waiting for allotted data to be gathered was enough to discourage me – LIDAR would suffice! 

The Trimble GeoXH 6000 at the summit of Hanter Hill

We now headed down to the bwlch and followed the green track of our ascent route back to Upper Hanter where the woman; Janet van der Linden, was still outside enjoying the morning’s shade.  We stopped and chatted, I joked that we had wondered if on our return we would be met with glasses of lemonade.  She smiled and went inside and brought out a jug of cold water with two glasses. 

A welcome sight; Janet with fresh chilled water

The water was refreshing and from a spring, it was very welcome.  We chatted about the old farm house and the route we had taken and where we were now heading.  This proved a much needed rest as even walking down hill in the increasing warmth proved tiring.  Having thanked Janet we headed down the continuation of the green track to the awaiting car and then headed northward toward Presteigne, where we stopped and replenished with goodies from the local Spar, before joining up with a narrow lane heading toward The Warren and Stonewall Hill, the latter our second Nation Top of the day. 

 

Postscript: 

Since the survey of these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position for some of these hills being prioritised in preference to that produced by the Trimble GeoXH 6000.

Survey Result: 

 

Hergest Ridge

Summit Height:  401.0m (converted to OSGM15, Trimble GeoXH 6000) (Pedwar addition under National Top status)

Summit Grid Reference:  SO 24693 55769 (Trimble GeoXH 6000)

Bwlch Height:  269.5m (LIDAR)

Bwlch Grid Reference:  SO 22053 55707 (LIDAR)

Drop:  131.5m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  32.80% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Hergest Ridge

Summit Height:  426.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SO 25435 56259 (from previous Trimble GeoXH 6000 survey)

Col Height:  269.5m (LIDAR)

Col Grid Reference:  SO 22053 55707 (LIDAR)

Drop:  157.4m (Trimble GeoXH 6000 summit and LIDAR col)

Dominance:  36.88% (Trimble GeoXH 6000 summit and LIDAR col)

 

 

Hanter Hill

Summit Height:  415.0m (LIDAR)

Summit Grid Reference:  SO 25199 57096 (LIDAR)

Bwlch Height:  346.9m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SO 25392 56820 (from previous Trimble GeoXH 6000 survey)

Drop:  68.1m (LIDAR summit and Trimble GeoXH 6000 bwlch)

Dominance:  16.41% (LIDAR summit and Trimble GeoXH 6000 bwlch)

 

 

For details on the survey of the English summit of Hergest Ridge and the bwlch survey of Hanter Hill

For further details please consult the Trimble Survey Spreadsheet